Abstract: The operation state of the FCC flue gas purification unit, which is designed for the 1.2Mt/a FCC unit in the refinery of CNOOC Huizhou Petrochemical Limited Company, was introduced. The unit, adopting wet desulfurization and dust removal technologies, run smoothly for one year and reaches the design requirement, including pollutant emission, energy consumption and CEMS instrument system. However, two problems were found during the operation of the purification unit: the suspended solids concentration fluctuation for the waste water, and the blue smoke plume. The problems were solved by the process modification, three type additives application and the operation parameter optimization.

Key words: FCC, flue gas purification, SO3, smoke plume, waste water, suspended solids